1. Field of the Invention
The present invention relates to a path searching circuit, a path searching method, and a path searching program and more particularly to the path searching circuit, the path searching method, and the path searching program being preferably employed in a CDMA (Code Division Multiple Access) communication system.
The present application claims priority of Japanese Patent Application No. 2003-019604 filed on Jan. 29, 2003, which is hereby incorporated by reference.
2. Description of the Related Art
In a CDMA demodulating circuit, a path diversity effect is achieved, conventionally, by path searching and rake combining. Quality of a radio wave received in a mobile telecommunication environment is degraded by a change in power levels and/or noises caused by multi-path fading. In an environment where a severe path change occurs, frequency of an error in detecting signal receiving path timing at time of searching a path becomes high, which causes degradation of a signal receiving characteristic. Therefore, advent of path searching processing is expected in which a stable path can be searched out of arriving paths and can be assigned to a finger.
A conventional path searching device is disclosed in, for example, Japanese Patent Application Laid-open No. 2001-36430, in which a judgment is made on whether or not an interpolation process to make a chip interval smaller is performed before and after each individual processing unit for every two or more processing units depending on the number of communication channels to be processed and the interpolation process is then performed, based on a result from the judgement, before and after each individual processing unit in a path searching processing steps.
However, in the above conventional technology, there is a deficiency that a path change in mobile telecommunications cannot be quickly tracked and responded, thus not enabling an excellent signal receiving characteristic.